Mandatory vs. Advisory

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From: Stevan Steve Allen (scallen@us.ibm.com)
Date: 01/16/03-01:51:52 PM Z


Subject: Mandatory vs. Advisory
Message-ID: <OF8ABC8B8C.1AAD2DBF-ON88256CB0.0007BF69@us.ibm.com>
From: Stevan Steve Allen <scallen@us.ibm.com>
Date: Thu, 16 Jan 2003 11:51:52 -0800




At my location we are attempting to evaluate the need to add NLM support to
our NFSv3 client due to NFSv4 mandatory locking...

Someone locally made the statement that NFSv4 mandatory locking is provided
solely to insure "data integrity".  And data integrity can only be provided
if everyone (all NFS versions) performs locking (e.g. no advisory locking
allowed).  To provide data integrity, a server implementation may decide to
enforce mandatory locking for NFSv3.  The last statement contradicts the
original NFSv3 protocol which assumes the nfs server is unaware of what
locks are held (by lockd) while processing a client read or write request.

The questions are:

o) Is anyone planning to enforce mandatory locking on their server for
NFSv3?
o) If a NFSv3 client does not support NLM and an NFSv3 server requires
mandatory locking (describes a failure case with no user bypass), are
both/neither considered to be abiding by the NFSv3 protocol?
o) Is it expected that all NFSv3 clients need to support NLM (or
unmonitored locking) because of mandatory locking?

Thanks for any clarification.


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